Hot top casing for casting molds



Nev. 23, 1965 P. DAVIDSON HOT TOP CASING FOR CASTING MOLDS OriginalFiled Dec. 21, 1959 s m M u m w o N T I T Y B United States Patent 1, 348 Claims. (Cl. 249-497) Matter enclosed in heavy brackets appears in theoriginal patent but forms no part of this reissue specification; matterprinted in italics indicates the additions made by reissue.

This invention relates generally to casting molds used in the casting ofsteel and other metals and more particularly to a hot top casingstructure adapted for use with ingot casting molds.

For a long time there has been a need in the casting hot top art for amold casing material which meets the requirements of good heatinsulation, good form resistance and low manufacturing cost. Whilevarious types of hot top casings have been provided in the past, thesehave been specifically designed to provide roughened sinkhead surfaceson the cast ingot so that the ingot may be suitably gripped by the tongsof lifting cranes.

An object of the present invention is to provide a cast.- ing mold hottop casing of simple construction which produces an ingot the sinkhcadof which has smooth surfaces so that the sinkhcad part of the ingot maybe used during subsequent ingot treatment rather than being wasted as inthe past.

Another object of the invention is to provide a hot top which results inorientation of the arising pipes and hour.- tions extending upwardly inthe ingot so that the portion of the ingot being returned as scrapduring subsequent ingot treatment is minimized.

According to the present invention it is possible to manufacture, at lowcost. casting mold hot tops having superior qualities. In accordancewith the invention the hot top includes a firm and relatively thincasing consist ing of an organic fibrous material, a fireproof material,and a binder. which casing is characterized in that it consists byweight of not less than 2% and not more than 20% (preferably not morethan 15%) organic fibrous material. 4-l0% binder, and the remainderfireproof material. For the organic fibrous material it has been provenadvantageous to use paper pulp, Waste paper or the like-cg, mechanicalpulp or a pulp of waste paper or the like possibly with an addition ofchemical pulp. As fireproof material may be used quartz, sand or anothersilicate; in some cases basic materials as burned dolomite, ClllClCl'S,or the like may be used. In the fireproof material may also be includedup to by weight of a fireproof fibrous material such as asbestos. Thebinding medium may be organic or inorganic. Of the first type there maybe mentioned glue, such as synthetic glue (e.g., synthetic resins orsilicone resin), glue manufactured from animal or vegetable rawmaterials (cellulose glue). Of the latter type may be mentionedfireproof cement or silicate of potassium (water glass). The casing maybe completely or partly surrounded by an insulated volume of air or byheat insulating material such as sand, bricks or the like.

cellulose glue.

Re. 25,915 Reissued Nov. 23, 1965 "ice It has been shown that hot topcasings in accordance with the invention are relatively inexpensive tomanufacture, have good storing and form resistance properties, goodinsulation qualities, and achieve smooth surfaces of the cast metal. Forexample, during the manufacture of a steel ingot with the use of hot topcasings in accordance with the invention the sinkhead obtains a smoothsurface as the pipes or liquations are concentrated in its uppermostpart. This is of great economical importance, since only a very smallpart of the steel in a sinkhead has to be returned as scrap.

Other objects and advantages of my invention will become apparent from astudy of the following specification when considered in conjunction withthe accompanying drawings in which:

FIG. 1 is a vertical section of the hot top easing taken along line l-1of FIG. 2;

FIG. 2 is a plan view of the hot top casing;

FIG. 3 is a sectional view taken through the mold and hot top;

FIG. 4 is a detailed sectional view of another embodiment of theinvention; and

FIGS. 5-7 are detailed sectional views of other hot top constructions.

As shown in FIGS. 35, the hot top casing 13 tapers upwardly and inwardlyand is supported at its lower edge on the shoulder portions 16 of thewall of the ingot mold 12. It is also possible, however, to place thehot top casing upon the upper circumferential surface of the ingot moldopening. As mentioned above the casing consists by weight of 240%(preferably 245%) organic fibrous material, 4-10% binder, and theremainder fireproof material. As especially preferred limits there maybe mentioned 25-13% by Weight organic fibrous material and 4.S-9%binder. Possibly also smaller quantities of other materials may beincluded. As examples of organic fibrous materials of suitableconsistency may be mentioned paper pulp, waste paper or the like (cg.mechanical pulp or pulp manufactured from waste paper, possibly havingan addition of chemical pulp). The suitability of the mentioned fiberpulp for this purpose is that the binding of the usually granular and/orpowder-formed fireproof material (cg. quartz) is facilitated, and alsothe casing is given a porosity which substantially increases itsinsulation qualities. It has also been shown that injurious gasformation is avoided by the use of the casing when the above mentionedcontents of the fibrous material are included.

As fireproof material, quartz or quartzite may be suitably used. Alsoother fireproof materials such as sand, certain other silicates, basicmaterials as burned dolomite and cinders and the like may be used. Ifdesired one may use up to about 10% (preferably 0-4'lt) by weightfireproof fiber material (as for example asbestos) mixed in the usuallygranular and/or powder-formed fireproof material. The [medium] averagegrain size for the fireproof material is to be below 1 mm., preferablybelow 0.3 mm. and often below 0.2 mm. Suitable limits for the [medium]average grain size may be 0.6-0.05 mm. The grain size may be stated asbeing below 45 mesh, preferably below [45] 100 mesh.

The binder in the casing may be glue, such as synthetic glue, e.g.synthetic resin or silicone resin, or glue manufactured of animal orvegetable raw materials such as Usually a sufficicnt quantity of binderis added to achieve satisfactory strength. In certain cases instead ofthe above mentioned binder an inorganic hinder such as fireproof cementor water-glass may be used.

As examples of suitable material compositions for the casing inaccordance with the invention may be mentioned the following:

(I) Mass or pulp composed [by] of waste paper and/or other mechanicalpulp, possibly mixed with some smaller quantities of chemical pulp,total 22% by weight, synthetic resin, glue or the like, 544% by weight,and the remainder fireproof material, preferably quartzite powder and/orthe like.

(2) Paper pulp and/or waste paper, 28i by weight, glue 5-896 and therest consisting of fireproof material.

(3) Paper pulp 341"? by weight (preferably about 3'1), asbestos 0.4?"0(preferably above 0%), glue 5-8% and the rest fireproof material,

As shown in FIGS. 14. the hot top casing 13 is formed with a lowerterminal surface 15 which contacts the shoulder surface 16 of the innerwall of the ingot mold 12 (FIG. 3).

The shoulder surface 16 is inclined to the vertical at an angle of 2l5,preferably 240". For small diameter variations between the ingot moldsof the same type and size the casing will be applied in such a way uponthe ingot mold that the total volume included in the casing and ingotmold (and thus the ingot Weight) will be substantially constant.

In the embodiment of FIG. 3, the inner wall portions of the ingot moldbelow and above the shoulder portion 16 may be formed with surfacesslightly inclined to the vertical and also to the surface of shoulderportion 16. The space 14 between casing 13 and upper part 17 of theingot mold is filled with sand, bricks or another insulating material.It is naturally also possible to efi cct mold insulation by enclosingair in a suitable manner in the space 14. Before or after theapplication of the casing it may be desirable to apply a sealing medium,such as asbestos, putty, wood wool, straw, glass wool or the like on orclose to the contact surface of the ingot mold and the casing 13 as at15, 16.

In FIG. 4 is shown an embodiment in which the ingot mold 12 terminatesat its upper end adjacent the shoulder portion 16. Above the ingot moldis placed an outer casing 19 of an insulating material, such asinsulating bricks, surrounded by an outer shell 20, and this outercasing 19 laterally supports the outer surface of the hot top casing.Between the outer casing 19 and the hot top casing 13 is arranged aspace 14.

Other modifications of the hot top casing are possible, of course. Theouter surface of the hot top casing may be supported by an outer casingand its lower edge may extend into the upper portion of the ingot mold.in FIG. 5 is shown a hot top, corresponding with that of FIG. 3, at theupper portion of which is provided a cover 13 above the space 14 whichspace is filled with insulating material, such as bricks.

The hot top casing 13 has been illustrated in FIGS. 1-6 as taperingupwardly and inwardly toward the center of the ingot mold, but thecasing may also have substantially vertical walls as illustrated in FIG.7.

A hot top casing formed in accordance with FIGS. 1-5 and '7 with orwithout the last mentioned cover provides the great advantage that steelor the like from the bloom does not to any substantial degree penetratebetween the casing and the inner wall of the ingot mold, on account ofwhich the risk of hot. cracks in the outer layer of the ingot inconnection with the stiffening of the ingot is avoided. Further there isobtained a smooth travel between hot top and ingot mold and in the ingotthe formation of pads or any other protuberances is avoided, which flawsordinarily would have been impossible to remove during rolling;consequently, the percentage of scrap in the ingot is materiallyreduced.

In the embodiments described above with reference to dtl FIGS. l5 and 7,the lower extremity 15 of the casing 13 is tapered and the outer surfaceof the tapered portion converges inwardly toward the inner surface. Forcertain types of ingot molds (FIG. 6) the extremity of the lower surfaceof the casing 21 may terminate in two angularly inclined surfaces 22joined by a common edge 23, which surfaces are contiguous with the wallsof a corresponding ledge in the inner wall of the mold.

The thickness of the casing (I3, 21) above the lower end supportingsurface or surfaces (15. 22) is generally constant and preferablybetween 5 and 15 mm. For a l.7-ton ingot the casing thickness should beapproximately 12 mm.

While in accordance with the patent statutes I have illustrated anddescribed the best forms and embodiments of my invention now known tome, it will be apparent to those skilled in the art that other changesmay be made in the apparatus described without deviating from theinvention as set forth in the following claims.

I claim:

1. A hot top casing for an ingot casting mold consisting of a moldedmixture of from 2 to lfi li by weight of a fibrous organic material, 4to 10% by weight of a binder, up to 4% by weight of an inorganic fibrousmaterial and the remainder consisting essentially of a granular fireproof material which is not disintegrated by the heat to which it issubjected in use selected from the group consisting of quartz, sand,refractory silicates, burned dolomite and cinders, said granularfireproof material having [a medium} an average grain size within therange from 0.6 to 005 mm. and said casing being relatively thin andhaving a smooth inner surface.

2. A hot top casing as defined in claim 1 wherein said binder is anorganic glue.

3. A hot top casing defined in claim 1 wherein said fireproof materialis quartz.

4. A hot top casing as defined in claim 1 wherein said organic fibrousmaterial includes cellulosic fibers less than 8% by weight, and saidbinder includes glue in the range of 48%.

5. A hot top casing as defined in claim 1 in which the percentage offibrous organic material is within the range from 2.5% to 13%.

6. A hot top casing for an ingot casting mold consisting of a moldedmixture of from 2 to lSWi by weight of a cellulose fibrous organicmaterial, 4 to lUPl: by weight of a resin binder, up to 4% by weight ofan inorganic fibrous material and the remainder consisting essentiallyof a granular fireproof material which is not disintegrated by the heatto which it is subjected in use consisting of refractory silicatecontaining material, said granular fireproof material having [a medium]on average grain size within the range from 0.6 to 0.05 mm. and saidcasing being relatively thin and having a smooth inner surface.

7. A hot top caring for an ingot costing llltilt'l consisting of amolded mixture of from 2 m 15% by Wt'lgllf of n fibrous organicmaterial, 4 to 109 by n't'lgln of (I binder, up to 4% by weight of aninorganic fibn'nrs material and the remainder ('OIISlAIiilg essentiallyof a granular treproof nullerinl which is not disintegrated by the heatto which it is subjected in use selected from the group consisting ofquartz, sir-ml, refractory silicates, lmrnml dolomite and ('l-fIClL'l'S,mid granular fireproof material having an (average grain size belowabout one mm. and said ctr-sing being relatively thin and having asmooth inner surface.

8. A ltOl top casing for an ingot casting: molt! consisting of nniolalccl mixture of from 2 to 15% by It'rlglit of u fibrous organicmaterial, 4 to 10% by tt't'iglit of a blni'ler. up to 4% by weight of onlnt'irgnnic fibrous material (nu! the remainder consisting essentiallyof a finely divided fireproof material which is not dirilttegmft'd byEli." llttl! m tt'ltltili i. ll .inlijetlccl ln mt .ttlttlt'tl from tln'grin/p t'cn'tiirn'ng of quartz, stnnl, refractory .slllctntnr, bnrnt'tldolomite and cinders, said casing being relatively thin and having asmooth inner surface.

References Cited by the Examiner The following references, cited by theExaminer, are 5 of record in the patented file of this patent or theoriginal patent.

Firth 22-147 Rowe 22-147 McDonald 22-147 Nicholas 22-147 Eayrs 22-193Charman et a1 22-147 Peterson 22-147 Gottschalk 22-147 MARCUS U. LYONS,Primary Examiner.

